Search found 40 matches
- Sat Mar 12, 2016 11:08 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Internal Energy of Isothermal Processes
- Replies: 2
- Views: 973
Re: Internal Energy of Isothermal Processes
The textbook has a nice passage that explains it quite well: "When an ideal gas expands isothermally, its molecules continue to move at the same average speed, so their total kinetic energy remains the same. Because there are no forces between the molecules, their total potential energy also re...
- Sat Mar 12, 2016 10:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Strongest Oxidizing/Reducing Agents
- Replies: 1
- Views: 445
Re: Strongest Oxidizing/Reducing Agents
Strongest reducing agents will have the lowest reducing potentials, the opposite for oxidizing agents.
- Sat Mar 12, 2016 10:51 pm
- Forum: Balancing Redox Reactions
- Topic: Winter 2012 Final
- Replies: 1
- Views: 498
Re: Winter 2012 Final
Look at the reaction they gave you. Note the changing oxidations states of Mn and Cl (compare products to reactants). Mn changes from +4 to +6 while Cl changes from +1 to -1. This indicates that Mn is undergoing oxidation, and thus on the anode side, and this indicates that Cl is undergoing reductio...
- Sat Mar 12, 2016 10:49 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Electrode
- Replies: 1
- Views: 445
Re: Electrode
No not always, you can have a mercury electrode, which is liquid.
- Sat Mar 12, 2016 10:48 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 2012 practice final#2A
- Replies: 3
- Views: 714
Re: 2012 practice final#2A
The question gives you no other information that could lead you to conclude that the pressure did actually change in the process of He leaking.
- Sat Mar 12, 2016 10:45 pm
- Forum: *Cycloalkenes
- Topic: Winter 2012 Final Q5
- Replies: 2
- Views: 702
Re: Winter 2012 Final Q5
Look at the carbons connected to the double bond. Now look at the atoms connected to those carbons. On the left side of the double bond, a C and an H are connected to the carbon you just located. C has a higher atomic number than H, so mark C. Now look at the right side of the double bond. Another C...
- Sat Mar 12, 2016 10:41 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Irreversible Isothermal
- Replies: 1
- Views: 486
Re: Irreversible Isothermal
Yes. Sometimes, you'll find that you'll need to use -deltanRT, which is the equivalent of -PdeltaV.
- Sat Mar 12, 2016 10:34 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Comparing heat capacities in Final 2011
- Replies: 1
- Views: 475
Re: Comparing heat capacities in Final 2011
You can also calculate it using the bond enthalpy table. Ethane has 6 C-H bonds and 1 C-C Bond, which when added together, will give a higher energy value than will Ethene with 4 C-H bonds, and 1 C=C bond.
- Sat Mar 12, 2016 10:31 pm
- Forum: *Alkenes
- Topic: Practice Final 2015, problem 10A
- Replies: 1
- Views: 526
Re: Practice Final 2015, problem 10A
If the double bond was a substituent, then you would need to name it as an alkene. In this case the double bonds are not substituents, or if they are, they are part of functional groups which you will have already named. We don't need to know about the phenol functional group.
- Sat Mar 12, 2016 10:26 pm
- Forum: *Cycloalkanes
- Topic: Ch.1 Q 16 Intro to O Chem
- Replies: 2
- Views: 608
Re: Ch.1 Q 16 Intro to O Chem
Step 1 is to number the substituents such that you have the lowest numbers. If we number from the methyls, the first methyl will be #1, the second methyl will be #1, and the isopropyl will be #3. If we number from the isopropyl, the isopropyl will be #1, the first methyl will be #2, and the second m...
- Sat Mar 12, 2016 10:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Winter 2014 Final Question 3
- Replies: 1
- Views: 448
Re: Winter 2014 Final Question 3
You want the highest Ecell value. To do that you need the highest reduction potential and the lowest reduction potential (Remember Ecell = Ecathode - Eanode; to get the highest Ecell value you want to subtract a low value from a high value). If you write out all the possible half reactions from the ...
- Sat Mar 12, 2016 10:05 pm
- Forum: *Chem3D
- Topic: Energy vs. Dihedral angle graph
- Replies: 1
- Views: 3023
Re: Energy vs. Dihedral angle graph
I'd start at 0 degrees because it's simply more practical, and convenient. Say for example, you have two bromine atoms, each attached to a carbon atom on an ethane molecule. At 0 degrees, both Br molecules would give the conformation steric strain, making it the highest energy conformation. Every si...
- Sat Mar 12, 2016 9:59 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Winter 2014 Final Q2A
- Replies: 2
- Views: 576
Re: Winter 2014 Final Q2A
There are less gas molecules in the products than there are in the reactants. Entropy is decreasing, going from disorder to order.
- Sat Mar 12, 2016 9:57 pm
- Forum: *Alkanes
- Topic: tert vs neo
- Replies: 3
- Views: 726
Re: tert vs neo
I suggest you search up Idean's Review Packet in this forum. The last page has a good visual representation of molecules with tert and neo, that should give you a good idea of their distinctions.
- Sat Mar 12, 2016 9:52 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: reaction enthalpy
- Replies: 1
- Views: 408
Re: reaction enthalpy
Yes to both. Ecell is the one that does not change.
- Fri Mar 11, 2016 10:17 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Drawing Cell Diagrams
- Replies: 1
- Views: 300
Re: Drawing Cell Diagrams
Leave the ends open.
- Fri Mar 11, 2016 10:09 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Steady State vs Pre equilibrium
- Replies: 1
- Views: 609
Re: Steady State vs Pre equilibrium
I'm pretty sure that we need to be aware that there are two methods - steadystate and pre-equilibrium - but that we only need to know pre-equilibrium for the final.
- Thu Mar 10, 2016 4:26 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Hydrolysis of Acetyl phosphate
- Replies: 1
- Views: 1761
Re: Hydrolysis of Acetyl phosphate
The question is essentially asking: How many moles of ATP do you need to hydrolyze in order to get the amount of energy needed to phosphorylate 1 mole of acetyl phosphate? In this case, the hydrolysis of 1 mole of ATP releases -30.5 kJ in energy. The hydrolysis of acetyl phosphate is -41 kJ/mol. The...
- Sun Mar 06, 2016 7:27 pm
- Forum: *Nucleophiles
- Topic: Why is H2O a nucleophile while CO2 is an electrophile?
- Replies: 1
- Views: 5117
Why is H2O a nucleophile while CO2 is an electrophile?
Title says all, thanks.
- Sun Feb 28, 2016 9:26 pm
- Forum: *Electrophiles
- Topic: Saturated and Unsaturated Hydrocarbons
- Replies: 2
- Views: 598
Re: Saturated and Unsaturated Hydrocarbons
Saturated hydrocarbons are organic compounds that contain single carbon-carbon covalent bonds, while unsaturated hydrocarbons are organic compounds that contain at least one double or triple bond. Unsaturated hydrocarbons will have kinks in their structures.
- Sun Feb 21, 2016 6:02 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetically Controlled vs. Thermodynamically Controlled
- Replies: 3
- Views: 1068
Kinetically Controlled vs. Thermodynamically Controlled
What do I tell if a reaction is kinetically controlled or thermodynamically controlled?
- Tue Feb 09, 2016 10:22 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Winter 2015 Midterm Q1 q
- Replies: 1
- Views: 461
Re: Winter 2015 Midterm Q1 q
In this case, this is a problem where both the copper kettle and water are at the same temperature and need to be raised to the same 100 degrees C. The problem that you're thinking about will usually involve something heated that's submerged in something at a different temperature. That's when you'l...
- Tue Feb 09, 2016 10:10 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 2015 Midterm #7
- Replies: 2
- Views: 620
Re: 2015 Midterm #7
In general, the half reactions and their corresponding reduction potentials will be given to us via formula/data sheet. In this case however, it is unnecessary to even know the reduction potentials of the reaction, as the standard cell potential will ultimately be 0 since the two half reactions are ...
- Tue Feb 09, 2016 9:52 pm
- Forum: Balancing Redox Reactions
- Topic: Midterm 2014 Question 8
- Replies: 1
- Views: 456
Re: Midterm 2014 Question 8
In this case we are trying to obtain the equation 2HF(aq) --> 2H+(aq) + 2F-(aq) in order to find it's Ka. In order to get this equation, the equation with the +3.03 V can't be the cathode, it needs to be the anode. By designating it as the anode half reaction, we'll then flip it accordingly, which w...
- Sun Feb 07, 2016 7:50 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: midterm 2011 question 6
- Replies: 1
- Views: 496
Re: midterm 2011 question 6
The most positive reduction potential (which would be the cathode) and the most negative reduction potential (which would be the anode) would create the largest cell potential. Remember, voltage would be calculated from Ecathode - Enanode. Hence, getting the largest voltage would require you to get ...
- Sun Jan 31, 2016 5:23 pm
- Forum: Balancing Redox Reactions
- Topic: Midterm material?
- Replies: 1
- Views: 467
Re: Midterm material?
It's up to and including electrochemistry, so up to page 56 in the course reader.
- Tue Jan 19, 2016 8:24 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Linear Molecule Rotation vs Nonlinear Molecule Rotation
- Replies: 1
- Views: 907
Linear Molecule Rotation vs Nonlinear Molecule Rotation
In the textbook, on page 8.7 it says that "linear molecules can rotate about two axes perpendicular to the line of atoms" and "nonlinear molecules can rotate about any one of three perpendicular axes". I am having trouble visualizing the nonlinear molecule rotation. Can someone c...
- Fri Jan 15, 2016 8:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: kJ vs kJ/mol
- Replies: 2
- Views: 1545
kJ vs kJ/mol
Is there a rule of thumb as to when our answers should have units kJ and when it should have units kJ/mol?
- Thu Jan 07, 2016 8:17 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Characteristics that give higher heat capacities?
- Replies: 3
- Views: 2380
Characteristics that give higher heat capacities?
I know that increasing molecular complexity usually means a higher molar heat capacity. Are there any other characteristics that could contribute to a higher molar heat capacity? Like greater bond strength?
- Fri Dec 04, 2015 1:14 pm
- Forum: *Titrations & Titration Calculations
- Topic: 2005 Final #7B - Sig Figs
- Replies: 1
- Views: 313
2005 Final #7B - Sig Figs
For the 2005 Final #7B, the answer given is 11.25 mL - 4 sig figs. When I calculated the answer, I rounded off to 11 mL - 2 sig figs. Did I miss something? Or is the answer incorrect?
- Sun Nov 29, 2015 8:27 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Lewis Vs Bronsted
- Replies: 2
- Views: 1902
Re: Lewis Vs Bronsted
In terms of the difference between the actual definitions, a Bronsted Acid is a proton donor and a Lewis Acid is an electron pair acceptor. A Bronsted Base is a proton acceptor and a Lewis Base is an electron pair donor. If you think about it, these definitions are telling you the exact same thing, ...
- Sat Nov 28, 2015 4:57 pm
- Forum: Lewis Structures
- Topic: Structure of N02
- Replies: 1
- Views: 599
Re: Structure of N02
Hi Deanna,
I remember asking about this myself. I was told that both structures are correct (the one with two double bonds, and the one with a triple bond and single bond), because each structure is a resonance structure. It's just something unique we'll have to remember.
Hope that helps.
I remember asking about this myself. I was told that both structures are correct (the one with two double bonds, and the one with a triple bond and single bond), because each structure is a resonance structure. It's just something unique we'll have to remember.
Hope that helps.
- Mon Nov 23, 2015 12:51 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Disregarding the X?
- Replies: 1
- Views: 348
Disregarding the X?
Do we disregard the x when calculating the equilibrium when K<10^-3 or K<10^-4?
- Sun Nov 15, 2015 2:23 pm
- Forum: Naming
- Topic: Naming -Water as a Ligand
- Replies: 1
- Views: 392
Re: Naming -Water as a Ligand
There is no difference between naming H2O and OH2 when writing the ligand. Both will be written as "aqua". Sometimes water is written as OH2 instead of H2O in order to make clear that the oxygen is the portion of the molecule that binds to the transition metal.
- Sun Nov 08, 2015 5:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chapter 11 #67 (The initial pressures are H2, 1.0 bar...)
- Replies: 1
- Views: 284
Chapter 11 #67 (The initial pressures are H2, 1.0 bar...)
Can someone explain to me why there is an "original" and "initial" part to the ICE table in solutions manual for question 67 of Chapter 11? Why can't we just use the given values in the question as the "initial" part for the ICE table for this problem? Thanks!
- Sun Nov 01, 2015 3:41 pm
- Forum: Properties of Light
- Topic: MT 2013 #4- Mass of a Neutron in relation to debrogiles
- Replies: 1
- Views: 375
Re: MT 2013 #4- Mass of a Neutron in relation to debrogiles
Hi! I believe you forgot to account for Avogadro's number when calculating for the mass of the neutron. Before converting straight to kg, you need to divide 1.00866g by Avogadro's number, otherwise you will simply have the mass for 1 mole of neutrons instead of the mass for a single neutron. From th...
- Sun Oct 25, 2015 9:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Homework question 4.13d
- Replies: 2
- Views: 639
Re: Homework question 4.13d
The central atom, most of the time, is the atom that has the least ionization energy. N has a lesser ionization energy compared to O, thus, N will be the central atom regardless of symmetry.
- Sun Oct 18, 2015 4:44 pm
- Forum: Lewis Structures
- Topic: Resonance for CO3 2-
- Replies: 1
- Views: 1983
Re: Resonance for CO3 2-
CO3 2- has a total of three resonance structures, with a C=O bond that appears once in each of the three resonance structures.
- Sun Oct 11, 2015 11:45 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Understanding the ml (Magnetic Quantum Number)
- Replies: 2
- Views: 2700
Re: Understanding the ml (Magnetic Quantum Number)
ml represents the different possibilities of the orientation of the subshell. I do not believe it is possible to determine which value of ml corresponds to which electron, as it is not possible to determine which value of ml corresponds to which orientation. However, I would verify that to ensure it...
- Sun Oct 04, 2015 2:40 pm
- Forum: Properties of Light
- Topic: Homework 1.65 Electromagnetic Radiation
- Replies: 2
- Views: 539
Re: Homework 1.65 Electromagnetic Radiation
Once you calculate for the wavelength that will break the C-C bond, you'll obtain a value that doesn't fall within the values/wavelengths of visible light. You'll find that this value actually falls under a different region of the electromagnetic radiation spectrum. This region (use Table 1.1 to det...